Introduction to the application of zinc oxide in the pressure sensitive ceramic device industry

16-11-2018

    SMM November 10th: On November 10th, at the 2018 (6th) China Zinc Oxide Industry Chain Trading Summit hosted by Shanghai Nonferrous Metals Co., Ltd., Gong Feng, General Manager of Zibo Zhongling Electronics Co., Ltd. introduced the application of zinc oxide in the varistor ceramics industry from the aspects of the history and development of ceramics, the development status and trends of varistor ceramics industry, and the application and requirements of varistor ceramics for zinc oxide powder.

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    The history and development of zinc oxide varistor ceramics

    Zinc oxide varistor ceramics have nonlinear volt-ampere characteristics. They were first discovered in the Soviet Union in the 1960s. In 1967, they were patented by Matsushita Electric Co., Ltd. and industrialized. It has created a new era of zinc oxide varistor ceramics. After 50 years of glorious history, it can be seen from the history of the past 50 years that the arresters of high-voltage power systems and varistors in the field of low-voltage electronics are widely used. The range of applications worldwide covers almost all electrical and electronic equipment. In the field of electronic ceramic materials science, a representative new material discipline has been formed that utilizes the grain boundary effect and is constantly evolving.

    Development Status and Trends of Pressure Sensitive Ceramic Device Industry 

    1. Lightning arrester industry In 1985, Xi'an High Voltage Electric Porcelain Factory, Fushun Electric Porcelain Factory and Xi'an Electric Porcelain Research Institute jointly introduced the manufacturing technology and main process equipment of Zinc Oxide Arresters of Japan Hitachi. The introduction of this technology not only meets the requirements of the rapid development of China's power industry, but also promotes the technological progress of varistor. After decades of development, China has become a major producer and application of zinc oxide surge arresters. Especially with the rapid development of China's power industry and high-speed rail industry, the consumption of zinc oxide in the arrester industry has shown a continuous growth trend. 

    2.  surge protector, varistor industry (including chip varistor) Relative to the arrester, varistor is more widely used, from small electric toothbrush in daily life, to nuclear power plants The electrical resistance of almost all electrical instruments related to electrical equipment, etc., can see the shadow of the varistor. 

    Application and Requirements of Pressure Sensitive Ceramics for Zinc Oxide Powders 

    Pressure sensitive ceramics are developing in the direction of high performance, high stability and high reliability. Under the conditions of the production formula and process of zinc oxide varistor ceramics, it is necessary to ensure the modernization of large-scale, high-volume production of high-quality, high-qualification rate, stable performance of pressure-sensitive ceramic sheets, using high-quality raw materials with stable physical and chemical properties. important. In a sense, high-quality, stable physical and chemical properties are the basis for ensuring the manufacture of high-quality varistor ceramics. 

    Zinc oxide accounts for about 90% of the mass composition of the varistor ceramic formulation, which is the main body of the final semiconductor structure. During the sintering process of the pressure sensitive ceramic, a zinc oxide crystal phase will be formed, and the phase is solid-dissolved with elements such as cobalt, manganese, lanthanum, aluminum, etc. by doping of the additive, and the zinc oxide crystal phase is transformed after sintering at 850-1200 °. It is made of pyrochlore and spinel to achieve the electrical properties required for pressure sensitive ceramics. Due to the influence of impurities on the performance of varistor ceramics, the purity of zinc oxide raw materials, the type of impurities, particle size, morphology and bulk density constitute important factors affecting the performance of varistor ceramics. For example, the particle size affects the change of spinel content during sintering and the distribution of elements such as cobalt, manganese and cerium in grains and grain boundaries, thereby affecting the properties of varistor ceramics. Generally, as the zinc oxide grains increase, the amount of cobalt and manganese dissolved in the zinc oxide grains increases, and the spinel content decreases, resulting in a decrease in the varistor voltage and a larger pressure ratio. As the particle size of zinc oxide is reduced, not only the slurry preparation is adversely affected, but also the firing shrinkage rate of the pressure-sensitive ceramic is increased. Therefore, when zinc oxide is selected, a powder having an average particle diameter of about 0.45 μm and a narrow particle size distribution should be selected. Moreover, high purity zinc oxide must be used. At present, the domestic varistor ceramic industry uses high quality zinc oxide manufactured by indirect method. The zinc oxide produced by other methods is not suitable for the manufacture of zinc oxide varistor ceramics because its purity is too low, the impurity content is too high, and the particle size is not suitable. Influential manufacturers in the pressure-sensitive ceramic industry are mainly; Weifang Aolong, Nantong Jinqi, Hangzhou Guangheng, Xinghua Sanyuan and so on. 

    In short, compared with other industrial fields, the demand for zinc oxide in the varistor ceramic industry is relatively small, but the quality requirements are higher and more special. Finally, he also called for the industry to increase research and development efforts for the development of varistor ceramics in China.




 [Reprinted need to keep the source - Shanghai Nonferrous Metals] [SMM dry goods] Zinc oxide in the varistor ceramics industry application profile https://news.smm.cn/news/100853183


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